The Privacy Protection Password is set when you turn your phone on for the first time and is needed if the sim was ever changed so if someone got your phone without your permission, they couldn't use a new sim without it. You must have set the password because I couldn't find anything about a default password like '0000' or '1234'. In any case, even a factory reset won't fix this as it is written to the system folder.
I think your options are limited here. You'll need to either reflash the firmware or send it back to the manufacturer for service.